QUASI-2-DIMENSIONAL ELECTRON-GAS AT SUBMONOLAYER COVERAGES OF CS ON INSB(110)

We present a complementary study of the space charge layer formation and band bending determination of caesium adsorption on InSb(110), by means of photoemission and high-resolution electron energy loss spectroscopy. At extremely low Cs coverage (below 0.01 monolayer), the Fermi level gets pinned into the InSb conduction band and an accumulation layer is formed. The quasi-two-dimensional (2D) behaviour of the accumulated carriers is experimentally deduced from the dispersion of the free-carrier plasmon. Eventually, further Cs deposition causes a reversed Fermi level pinning, with the formation of a depletion layer at saturation coverage.